Method for measuring magnitude of radio wave along a subway line, and an apparatus for said method

Abstract

The measuring apparatus according to the present invention searches each of subbands divided from a target band set with respect to the Frequency Distribution Information (FDI) obtained periodically to find a unit band corresponding to a maximum frequency component among unit bands pertaining to said each subband; marks the found unit band as a Dominant Unit Band (DUB); organizes a DUB distribution table by collecting a plural pieces of the FDI as much as a predetermined time; checks a distribution locus of DUBs on the organized DUB distribution table. And, if it is confirmed that the DUB distribution table shows a specific distribution pattern corresponding to an acceleration sound, etc., the measuring apparatus makes a measured intensity to be identified as an intensity measured at a start position of a platform or a tunnel section, based on the time when the specific distribution pattern appears.

What is claimed is: 
     
       1. An apparatus for detecting surrounding sounds while moving with a moving object,
 a sound analyzing unit configured to obtain, every predetermined interval, frequency distribution information of a sound for the predetermined interval, the sound being generated around the apparatus; and 
 a control unit configured to determine the moving object to be in a particular movement state corresponding to one of specific sounds generated in surroundings through determination, based on the obtained frequency distribution information, of whether or not said one of the specific sounds is generated, each of the specific sounds being a predetermined sound from which a movement state of the moving object is identifiable, 
 wherein the control unit is further configured
 to search each of subbands divided from a target band, with respect to the frequency distribution information that the sound analyzing unit obtains periodically, to find a unit band corresponding to a maximum frequency component among unit bands, each with a designated bandwidth, pertaining to said each subband, and to mark the found unit band as a Dominant Unit Band (DUB), 
 to check a distribution locus of DUBs on a DUB distribution table organized by collecting a plural pieces of the frequency distribution information as much as a predetermined time, in order to confirm whether the distribution locus matches with any one of intrinsic patterns preset respectively for the specific sounds, each of said plural pieces of the frequency distribution information, in the DUB distribution table, consisting of the subbands, each containing the marked DUB, and 
 to determine that said one of the specific sounds has been generated, if it is confirmed that the distribution locus of DUBs matches with one intrinsic pattern preset for said one specific sound. 
 
 
     
     
       2. The apparatus of  claim 1 , further comprising a storage unit configured to store measured information,
 wherein the control unit is further configured
 to receive measured intensity of radio wave and to store the measured intensity in the storage unit together with information on measurement time, and 
 in case of confirmation that the distribution locus of DUBs on the DUB distribution table matches with said one intrinsic pattern, to determine a time point later by a designated time interval, based on a time at which the matching distribution locus appears, as a boundary time point, and to record information for causing a radio wave intensity, which has the information on measurement time closest to the determined boundary time point among measured intensities stored in the storage unit, to be identified as an intensity measured at a start position of a platform or a tunnel section, and 
 
 wherein the moving object is an electric train. 
 
     
     
       3. The apparatus of  claim 2 , wherein the control unit is configured to record information for causing a radio wave intensity, which has the information on measurement time closest to the determined boundary time point, to be identified as an intensity measured at a start position of a tunnel section, in case a distribution locus of DUBs matching with a first intrinsic pattern preset for a sound to be generated when an electric train accelerates is detected from any one of DUB distribution tables being organized, or as an intensity measured at a start position of a platform, in case a distribution locus of DUBs matching with a second intrinsic pattern preset for a sound to be generated when an electric train decelerates is detected. 
     
     
       4. The apparatus of  claim 3 , wherein the control unit is configured to determine the boundary time point by applying length of the time interval differently depending on an additional condition of whether a specific signal caused from a sound to be generated in an electric train just prior to start has been detected or not before detection of a distribution locus of DUBs matching with the first intrinsic pattern, in case the distribution locus matching with the first intrinsic pattern is detected from said any one of the DUB distribution tables, or depending on an additional condition of whether a specific signal caused from a sound to be generated in an electric train just after stop is detected or not within a specified time after detection of a distribution locus of DUBs matching with the second intrinsic pattern, in case the distribution locus matching with the second intrinsic pattern is detected from said any one of the DUB distribution tables. 
     
     
       5. The apparatus of  claim 4 , wherein the specific signal is a specific sound that is generated to notify passengers that an electric train is going to start or has stopped, and
 the control unit is configured to judge detection of the specific sound based on whether a distribution locus of DUBs matching with a third intrinsic pattern preset for the specific sound is detected from the DUB distribution tables being organized. 
 
     
     
       6. The apparatus of  claim 4 , wherein the specific signal is a change in magnitude of a sound heard inside a carriage of an electric train when its doors are opened or closed, and
 the control unit is configured to determine that the specific signal is detected when a surrounding sound detected by the sound analyzing unit changes more than a threshold value within a predetermined period of time. 
 
     
     
       7. The apparatus of  claim 3 , wherein the control unit is configured to record station identification information that uniquely identifies a subway station corresponding to a platform with respect to measured intensities from a measured radio wave intensity, which information indicative of measurement at a start point of the platform is recorded in relation with, to another measured radio wave right adjacent to a measured intensity which information indicative of measurement at a start point of a tunnel section is recorded in relation with. 
     
     
       8. The apparatus of  claim 7 , further comprising a communication unit configured to be capable of communicating with an Access Point (AP) providing a wireless communication network locally within a limited area according to a specific signaling method, wherein the control unit is configured to obtain the station identification information for the corresponding platform through searching a list of APs, which have been installed in platforms of subway stations, for an identifier of a certain AP provided by the communication unit. 
     
     
       9. The apparatus of  claim 2 , further comprising a communication unit configured to be capable of communicating with an AP providing a wireless communication network locally within a limited area according a specific signaling method, wherein the control unit is configured:
 to check whether or not an arbitrary AP of which identification information is provided from the communication unit is an AP installed in a platform of a subway station; 
 if it is confirmed that the arbitrary AP is installed in a platform, to determine a time point, which is a designated offset time apart from a time at which the arbitrary AP is detected, as a boundary time point; and 
 to record information for causing a radio wave intensity, which has the information on measurement time closest to the boundary time point determined by reflecting the offset time among measured intensities stored in the storage unit, to be identified as an intensity measured at a start position of a platform. 
 
     
     
       10. The apparatus of  claim 9 , wherein the control unit is further configured to uniquely identify the platform where the arbitrary AP is installed, and to use time information pre-designated for the identified platform as the offset time. 
     
     
       11. The apparatus of  claim 2 , further comprising a sensor for detecting magnitude of acceleration acting on the apparatus,
 wherein the control unit is further configured to determine the boundary time point, in case a distribution locus of DUBs matching with the intrinsic pattern is detected from any one of DUB distribution tables being organized, by applying length of the time interval differently depending on an additional condition of whether steady change of the acceleration magnitude for a predetermined time or more is detected before or after a detection time of the distribution locus. 
 
     
     
       12. The apparatus of  claim 2 , further comprising:
 a photographing unit configured to take pictures outside a window of an electric train; and 
 an image analyzing unit configured to obtain a motion vector of an image frame from the pictures being taken, 
 wherein the control unit is configured to determine the boundary time point, in case a distribution locus of DUBs matching with the intrinsic pattern is detected from any one of DUB distribution tables being organized, by applying length of the time interval differently depending on an additional condition of whether the motion vectors being obtained sequentially before or after a detection time of the distribution locus are steadily changed in magnitude for a predetermined time or more. 
 
     
     
       13. The apparatus of  claim 4 , wherein the control unit is configured to apply the time interval to determination of the boundary time point after setting the time interval to be longer when the additional condition is not satisfied as compared with when the additional condition is satisfied. 
     
     
       14. The apparatus of  claim 1 , wherein the target band is set to have a bandwidth narrower than entire bandwidth of the frequency distribution information for audible sounds being obtained by the sound analyzing unit. 
     
     
       15. The apparatus of  claim 2 , wherein the control unit is configured to be capable of applying the time interval to determination of the boundary time point after setting the time interval differently depending on order of an carriage, on an electric train, where the apparatus is placed for measuring a radio wave. 
     
     
       16. The apparatus of  claim 2 , further comprising a radio wave measuring unit that is detachably connected to the apparatus and is configured to measure intensity of a radio wave and to transmit the measured intensity to the control unit,
 wherein the radio wave measuring unit is configured to measure intensity of a low frequency electromagnetic wave, which is abbreviatedly called as ELF or ELFMW. 
 
     
     
       17. The apparatus of  claim 2 , further comprising a radio wave measuring unit that is integrated into the apparatus and is configured to measure intensity of a radio wave and to transmit the measured intensity to the control unit,
 wherein the radio wave measuring unit is configured to measure intensity of radio signals for providing mobile communication. 
 
     
     
       18. The apparatus of  claim 1 , wherein the control unit is configured to organize the DUB distribution table in such a manner that a predetermined ratio of the DUB distribution table includes pieces of frequency distribution information having been included in latter portion of a DUB distribution table organized just before. 
     
     
       19. A method, conducted by an apparatus to be moved with an moving object, for using sounds generated in surroundings, the method comprising:
 a first step of obtaining, every predetermined interval, frequency distribution information of the sounds for the predetermined interval; 
 a second step of searching each of subbands divided from a target band set with respect to the frequency distribution information obtained periodically to find a unit band corresponding to a maximum frequency component among unit bands, each with a designated bandwidth, pertaining to said each subband, marking the found unit band as a Dominant DUB, and organizing a DUB distribution table by collecting a plural pieces of the frequency distribution information as much as a predetermined time, each of said plural pieces of the frequency distribution information, in the DUB distribution table, consisting of the subbands, each containing the marked DUB; 
 a third step of checking a distribution locus of DUBs on the organized DUB distribution table in order to confirm whether the distribution locus matches with any one of intrinsic patterns preset respectively for specific sounds; and 
 a fourth step of determining that one of the specific sounds has been generated, if it is confirmed that the distribution locus of DUBs matches with said any one intrinsic pattern, and determining the moving object to be in a particular movement state corresponding to said one specific sound, 
 wherein the specific sounds are sounds to be generated depending on movement state of the moving object. 
 
     
     
       20. The method of  claim 19 , further comprising a step of continuously measuring intensity of a received radio wave, and storing each measured intensity together with information on a corresponding measurement time,
 wherein the moving object is an electric train, and 
 wherein the fourth step further comprises: determining, in case of determining the moving object to be in the particular movement state corresponding to said one specific sound, a time point later by a designated time interval, based on a time at which one DUB distribution table is organized, as a boundary time point, said one DUB distribution table being a table including the distribution locus of DUBs on which the determination of the particular movement state is based; and recording information for causing an intensity, which has the information on measurement time closest to the determined boundary time point among the stored intensities, to be identified as an intensity measured at the start position of a platform or a tunnel section.